To arouse a bidding motivation of a bidder even if confirming no other bidder to become a rival for being executed on Internet in an auction of a system in which a bidding price is lowered with the time lapse and a person who bids first makes a successful bid.

This auction system includes a function, in performing the auction of the aforementioned system on Internet, adapted to interrupt a transaction when a numerical value of a time from starting the auction becomes equal to a generated random value, when a price calculated by substituting the generated random value for a prescribed arithmetic expression becomes equal to the bidding price, or when random numbers are repeatedly generated and a generated random number becomes equal to a preset numerical value. This auction system solves the above problem by disturbing the bidder with a possibility that the transaction may be abruptly interrupted by a bidder.